Harbors and marinas where boats and yachting ships berth are often equipped with floating moorage, composed of main floating pontoons and secondary floating pontoons (also called finger pontoons or finger piers) which are usually disposed at right angles from the main floating pontoons. The secondary pontoons are used for mooring and separating the ships, and for gaining access to these ships. Each main pontoon and the corresponding secondary pontoons constitute a floating boom.
The floating booms of a harbor are usually fixed or secured permanently, and are separated from one another by access channels which enable ships to maneuver for entering or leaving the floating booms. These access channels have commonly a width which is 1.5 to 2 times the average length of the ships which are received in the floating booms.
However, the presence of these multiple access channels results a significant loss of mooring surface in the harbor, and therefore a large loss in the number of ships which can be berthed in the harbor.
To mitigate this drawback, it has already been proposed to provide maneuvering devices for moving the floating booms relative to one another, in order to:                bring the booms together for obtaining a compact configuration of the floating booms when no ship is to enter or leave the floating booms;        and separate some of the booms for creating the access channels on demand.        
GB-A-2 236 716 discloses such a movable floating moorage including at least a set of n parallel floating booms, n being an integer larger than 1 and each floating boom comprising a main floating pontoon extending along a first horizontal direction which is common to all main pontoons of the set of floating booms;
said movable floating moorage further including an actuating system including at least one flexible line which extends in a second direction substantially perpendicular to said first direction and adapted to selectively move each floating boom in both ways in said second direction.
In this document, flexible lines are connected to the floating booms at one end thereof in the first direction, while the opposite end of each boom is connected to a sliding shoe which is driven and guided along an elongate member such as a rail sliding on a fixed pontoon.
One problem associated with this conception is that the driven pontoons are moveably connected to a rigid elongate member which controls the sliding movement of the driven pontoons which is not compatible with the flexibility necessary for a boom to adapt to the natural movements of the surface of the water.
Another problem associated with this conception is that the floating booms may become blocked due to the jamming of their sliding connection with the above mentioned rigid elongate member. Further, this conception is not readily adaptable on existing floating moorages and requires heavy investment.